Valves

ABSTRACT

A flap valve comprising a frame having an opening therein and a door adapted to close said opening out of which liquid may flow to a region containing another liquid the level of which may vary, said door being, in use, hinged above the opening with the opening arranged below the highest level reached by liquid in said region, the door comprising a portion of a density selected to be less than that of the liquid in said region and a portion of a density selected to be higher than that of the liquid in said region, the relative amounts of the low density portion and the high density portion being selected so that the overall density of the door is slightly greater than that of the liquid in said region.

United States Patent [1 1 [111 3,809,1 19 Cave 7 5] May 7, 1974 [54] VALVES 1,992,495 2/1935 Lynde 137/5257 [75] Inventor: Gordon Milford Cave, Solihull, I

England Primary Exammer--Robert G. Nilson Attorney, Agent, or Firm-Norris & Bateman [73] Assignee: Coplastix Limited, Worcestershire,

England 57 ABSTRACT [22] Filed: May 1, 1972 211 App]. N01: 248,989

[52] US. Cl. l37/527.8, 137/527.6 [51] Int. Cl. Fl6k 15/03 [58] Field of Search... 137/525.3, 525.7, 525-5278 [56] References Cited UNITED STATES PATENTS 3,613,720 10/1971 Welch l37/527.8 3,292,658 12/1966 Scaramucci.. 137/5253 3,366,137 l/l968 Hansen 137/5278 X 314,107 /1885 Chappeli 4 137/527 X 2,649,495 8/1953 Kennedy 137/5278 X 1 j l l t 1 l l A flap valve comprising a frame having an opening therein and a door adapted to close said opening out of which liquid may flow to a region containing another liquid the level of which may vary, said door being, in use, hinged above the opening with the opening arranged below the highest level reached by liquid in said region, the door comprising a portion of a density selected to be less than that of the liquid in said region and a portion of a density selected to be higher than that of the liquid in said region, the relative amounts of the low density portion and the high density portion being selected so that the overall density of the door is slightly greater than that of the liquid in said region.

10 Claims, 2 Drawing Figures This invention is concerned with improvements inor relating to the manufacture of valves, especiallyflap valves.

Valves are in common use today, often known as tidal flapvalves; these comprise a cast iron door hinged on a verticalwall above an opening therein, so thatthe door lies over the opening. Such valvesmay be positioned in sea walls, banks of tidal rivers or banksof other watercourses in which water level varies. The weight of the door normally keeps the door closed over the opening but should fluid pressure of sewage or other effluent build up sufficientlyin thepipe leading to the opening, to overcome the weight of the door, the door opens under the pressure and allowseffluent to escape. However, should a greaterpressure be exerted on the outer side of thedoor, for exampleby a hightide then the door is closed firmly and fluid in the pipe cannot escape until thepressure on the outside ofthe door is sufficiently reduced, for example whenthetide ebbs. Such flap valves have suffered from various disadvantages. They are very insensitive and a relativelyhigh pressure in the pipe has been necessary to open the valve and allow fluid to escape even in the absence of a pressure on the outer side of the doorz this disadvantage has been overcome, where necessary, by using a addition, the door has sometimes been found to fly open so violently that it has become jammed in the open position. Moreover the door is likely to be attacked by corrosion and, especially where the door is not counterbalanced, to suffer damage to the hinges, causing the valve to seize up.

It is therefore an object of the present invention to provide an improved flap valve, wherein the above mentioned disadvantages are obviated or at least alleviated.

According to the present invention, there is provided a flap valve comprising a frame having an opening therein and a door adapted to close said opening out of whichliquid may flow to a region containing another liquid the level of which may vary, said door being in use, hinged above the opening with the opening arranged below the highest level reached by liquid in said region, the door comprising a portion of a density selected to be less than that of the liquid in said region and a portion of a density selected to be higher than that of the liquid in said region, the relative amounts of the low density portion and the high density portion being selected so that the overall density of the door is slightly greater than that of the liquid in said region.

The invention will become more clear from the following description with reference to the accompanying drawings which illustrate, by way of example only, a tidal flap valve embodying the invention.

Of the drawings:

FIG. 1 is a front view of the illustrative flap valve:

2 and FIG. 2 is a vertical section of an upperportion of the illustrative valve.

The flap'valve comprises a framehaving an opening j therein and a door hinged to the frame adapted to close the opening andapassage about which the frame is adapted to be secured (with the opening in alignment withthepassageand ahingeportion above the opening) out of which passage liquid mayflow through the opening to a region containing ia liquid the level of which varies, the opening being disposed below the highest level reachedbytheliquid at a desired height abovean averagelevel of the liquid in said region. The door comprises a foamsplastics portion of a density less thanthat of the liquid insaid region, and a portion comprising a plurality of steel bars of a density higher than thatofthe liquid in said region. The door comprisessufficient steel bars to raise the apparent density of the door above that of the liquid in the region. Where the liquid in said region is sea waterithe specific gravity of the door is selected to be greater than 1.03

and preferably not more than 2.00.

flow, withthe projection 5 horizontal.

Theflap valve also comprises ahinge arrangement 7 by which a door 8 maybe secured to the frame 4. The

hinge 7 comprises a flexible hinge strip 12 of a suitable plastics material, for example a non-cellular polyurethane, clamped by means of a backing piece 26 and bolts 24 tothedoor8, and to the frame 4 by means of a plastics retainingstrip 14 and bolts10 threaded into a metal plate 11 at the rear of the frame, the strip 14 being positionedbelow and adjacent the projection 5. Friction, grit and water-resistant cloth 13 is interposed between the hinge-strip 12 and door 8 and between the hinge-strip 12 and frame 4 to ensure that the hingestrip 12 is gripped securely.

The door 8 is of a sandwich construction and comprises outer layers 16 of a suitable plastics material, for example rigid polyvinyl chloride with wear-resistant skins of a suitable abrasion andimpact-resistantresin, and a core 18 of shear-resistant plastics foam, for example rigid polyvinyl chloridefoam. The core 18 isentirely encased within the layers 16. Steel bars 20 are enclosed within the core and extend across the door 8 parallel with the projection and also across the gap between the outer layers 16 ensuring thatthe outer layers remain spaced apart by a desired amount. Bolts 24 are threaded into an upper one of the bars 20. If desired vertically disposed bars may also be included in the structure. The bars 20 reinforce the door 8 rendering it more rigid and resistant to warping.

The door 8 further comprises a foam rubber sealing member .22 bonded by a suitable adhesive to the inner face 23 of thedoor and seating against a seating portion a thickened lower portion upwardly until at an uppermost portion it merges with the outer surface 30 of the frame 4. The rubber sealing member 22 seats against a flat, annular outer surface of the seating portion 28. Thus when the flap valve is secured as aforementioned the door 8 slopes at a slight angle from the vertical downwardly and outwardly and the weight of the door 8 assists in keeping it seated firmly against the seating portion 28 of the frame.

The number of the bars is selected so that the overall density of the door is just greater than the density of the liquid which flows on the outer side thereof for example where a pipe which the valve is to close is to communicate with the sea, the specific gravity of the door is selected to be just greater than that of sea water viz. just over 1.03. The density of the door may be adjusted by the inclusion of a suitable number of steel bars so that the door has a desired resistance to opening and a certain minimum pressure is required in the pipe to open the door, provided that the apparent density is higher than that of the liquid which flows on the outer side.

The door is of a corrosion resistant material and the hinge arrangement is inherently most unlikely to seizeup. The valve is highly sensitive in use without the need for any counter-balance system.

What is claimed is:

l. A flap valve comprising a frame, means defining an opening through said frame, a valve seating extending around said frame opening, a door adapted to seat on said seating thus to close said opening, and a flexible hinge strip hingedly attaching said door to said frame above the opening, said door comprising an outer casing of rigid plastics material wholly containing a core of at least one other material having a greater specific gravity than said'casing material, and the overall density of the door being determined by the proportions of said materials.

2. A flap valve according to claim 1, wherein said core comprises a foamed plastics material and at least one material having a specific gravity greater than that of said foamed plastics material and that of said outer casing.

3. A flap valve according to claim 2, wherein said outer casing comprises two spaced apart layers of rigid polyvinyl chloride having wear-resistant skins of an abrasion and impact-resistant resin, and said core is of shear-resistant foamed polyvinyl chloride containing at least one steel bar.

4. A flap valve according to claim 1, wherein said valve seating has an inclined surface which when the flap valve is disposed vertically with the flexible hinge strip uppermost causes the door in its closed position to slope at an angle relative to a vertical plane, whereby the weight of the door assists in keeping it seated firmly against said valve seating.

5. A flap valve according to claim 4, wherein a resilient sealing member is secured to the inner face of said door and adapted to abut said valve seating when the door is closed thus to seal the opening against the flow of liquid therethrough.

6. A flap valve according to claim 1, wherein said frame is of plastics material and of annular form and includes a plurality of holes for securing same to a wall about said opening, said door being generally circular and hingedly secured to said frame at an arcuate portion thereof.

7. A flap valve according to claim 1, wherein the specific gravity of the door is selected to be greater than 1.03 and less than 2.00.

8. A flap valve comprising a frame, an opening in said frame anda door adapted to close said opening out of which liquid may flow to a region containing another liquid the level of which may vary, said door being, in use, hinged above the opening with the opening arranged below the highest level reached by liquid in said region, the door comprising a portion of a density selected to be less than that of the liquid in said region and a portion of a density selected to be higher than that of the liquid in said region, the relative amounts of the low density portion and the high density portion being selected so that the overall density of the door is slightly greater than that of the liquid in said region, said low density portion of said door comprises an outer casing of rigid plastics material containing a core of foamed plastics material, and said high density portion comprising at least one steel bar disposed within said outer casing.

9. A flap valve according to claim 8, wherein said outer casing comprises two spaced apart layers of rigid polyvinyl chloride having wear-resistant skins of an abrasion and impact-resistant resin, and said core is of sheer-resistant foamed polyvinyl chloride.

10. A flap valve according to claim 8, wherein said steel bar extends across the door and also across the space between the faces of said outer casing. 

1. A flap valve comprising a frame, means defining an opening through said frame, a valve seating extending around said frame opening, a door adapted to seat on said seating thus to close said opening, and a flexible hinge strip hingedly attaching said door to said frame above the opening, said door comprising an outer casing of rigid plastics material wholly containing a core of at least one other material having a greater specific gravity than said casing material, and the overall density of the door being determined by the proportions of said materials.
 2. A flap valve according to claim 1, wherein said core comprises a foamed plastics material and at least one material having a specific gravity greater than that of said foamed plastics material and that of said outer casing.
 3. A flap valve according to claim 2, wherein said outer casing comprises two spaced apart layers of rigid polyvinyl chloride having wear-resistant skins of an abrasion and impact-resistant resin, and said core is of shear-resistant foamed polyvinyl chloride containing at least one steel bar.
 4. A flap valve according to claim 1, wherein said valve seating has an inclined surface which when the flap valve is disposed vertically with the flexible hinge strip uppermost causes the door in its closed position to slope at an angle relative to a vertical plane, whereby the weight of the door assists in keeping it seated firmly against said valve seating.
 5. A flap valve according to claim 4, wherein a resilient sealing member is secured to the inner face of said door and adapted to abut said valve seating when the door is closed thus to seal the opening against the flow of liquid therethrough.
 6. A flap valve according to claim 1, wherein said frame is of plastics material and of annular form and includes a plurality of holes for securing same to a wall about said opening, said door being generally circular and hingedly secured to said frame at an arcuate portion thereof.
 7. A flap valve according to claim 1, wherein the specific gravity of the door is selected to be greater than 1.03 and less than 2.00.
 8. A flap valve comprising a frame, an opening in said frame and a door adapted to close said opening out of which liquid may flow to a region containing another liquid the level of which may vary, said door being, in use, hinged above the opening with the opening arranged below the highest level reached by liquid in said region, the door comprising a portion of a density seLected to be less than that of the liquid in said region and a portion of a density selected to be higher than that of the liquid in said region, the relative amounts of the low density portion and the high density portion being selected so that the overall density of the door is slightly greater than that of the liquid in said region, said low density portion of said door comprises an outer casing of rigid plastics material containing a core of foamed plastics material, and said high density portion comprising at least one steel bar disposed within said outer casing.
 9. A flap valve according to claim 8, wherein said outer casing comprises two spaced apart layers of rigid polyvinyl chloride having wear-resistant skins of an abrasion and impact-resistant resin, and said core is of sheer-resistant foamed polyvinyl chloride.
 10. A flap valve according to claim 8, wherein said steel bar extends across the door and also across the space between the faces of said outer casing. 